1. Team Lead: David Gustafson Tyler Hawkins Nick Brown Bryce Holmgren
Cirrus LSA Wing Design
Team Lead: David Gustafson
Tyler Hawkins
Nick Brown
Bryce Holmgren

2. Project Goals Utilize Edge Bonding Try New Light Weight Materials
Incorporate Spin Resistance
Total Weight Constraint
< 170 lbs for entire wing

3. Obstacles Edge Bonding vs. Required Strength and Existing Practice
New Materials
Cost
Performance
Spin Resistance vs. Manufacturing Simplicity
All of These vs. Weight and Performance

4. Areas of Design and Analysis
Loads Analysis
Aerodynamic Design
Materials Research and Testing
Structural Design

5. Aerodynamics and Control Bryce Holmgren
Cirrus Wing
Aerodynamics and Control
Bryce Holmgren

6. Aerodynamics Design Constraints
Light Sport Aircraft Requirements
Maximum Gross Weight: 1,320lbs
Maximum Stall Speed: 45 knots
Required Lift Coefficient to Meet Requirements: >1.60
Other Considerations
Spin Resistant Design
Enhanced Stall Performance

7. Aerodynamics Analysis Tools – XFLR5 Developed by MIT
Contains Airfoil Generation Tool Called Xfoil
Recommended by Cirrus for Preliminary Design Analysis

8. Aerodynamics Initial Wing Design Parameters Wing Span: 30 ft
Wing Area: 125 square ft
Airfoil Database – University of Illinois at Urbana-Champaign

9. Aerodynamics
Final Airfoil - NASA/Langley LS(1)-0417mod (also known as the GA(W)-1 airfoil)

10. Aerodynamics
Drooped Leading Edge
Enhanced Spin Resistance

11. Aerodynamics Drooped Leading Edge vs Standard Airfoil

12. Aerodynamics Wing Model in XFLR
Plane weight of 1500 lbs and at 44 knots
Lift Coefficient of 1.64 at 17˚ angle of attack

13. Aerodynamics Design Summary
Parameter
Dimension
Wing Area
ft^2
Wing Span
30 ft
Root Chord
4.5 ft
Tip Chord
3.7 ft
Mean Aerodynamic Chord
4.11 ft
Wing Loading
12.2 lbs/ft^2
Aspect Ratio
7.3
Taper Ratio
1.2
Dihedral Angle
5 Degrees
Max Lift Coefficient
19 Degrees Angle of Attack

14. Aerodynamics
Improvements
Less Aggressive Camber
Different Tip Airfoil

15. Controls Flaps Fowler Flaps Area: 24.4 ft^2 Ailerons
Differential Ailerons
Area: 12 ft^2

16. Cirrus Wing
Materials
Nick Brown

17. LSA FAA definition Max gross takeoff weight = 1320 lbs
Max stall speed = 45 knots
Maximum speed in level flight = 120 knots

18. ASTM F 2245-07 guidelines Limit load factors
Ultimate load factor of safety = 1.5
Special ultimate S.F.s for hinges, bearings, pins, control components
Flight conditions
Design speeds

19. Design speeds 45 knots = Stall speed (LSA)
99.6 knots= Minimum maneuvering Speed
108 knots = Minimum cruise
120 knots = Maximum cruise (LSA)
160 knots = Dive speed

20. Flight envelope
VA VC,max VD Vs

21. Total Loads Level flight 1320 lbs Design Limit load = 5280 lbs
Ultimate load = 7920 lbs (for 3 seconds)

22. XFLR5 Simulations Data (spreadsheet)
Various A.O.A. and Reynolds numbers
Wing panels
Data (spreadsheet)
Aerodynamic coefficients
Lift, drag, and moment forces

23. XFLR5

24. XFLR5

25. XFLR5

26. Distribution

27. Shear and bending Integrate ultimate load equations
From 0(root) to 8ft (airfoil switch)
F = x
From 8ft to tip (15ft)
F = x x

28. Torsion/control loads
75% positive maneuvering load, plus torsion from max aileron displacement
Gust loads at VF with flaps extended (7.5 m/s)

29. Gusts Symmetric vertical gusts (up and down) 15 m/s at VC
7.5 m/s at VD

30. Composite Panels & Adhesives David Gustafson
Cirrus Wing
Composite Panels & Adhesives
David Gustafson

31. Composite Panels
Panels are fiberglass on both sides with a core in the middle consisting of either foam or a honeycomb structure

32. Core Options

33. Final Core Material HT Diab 61 Aramid Core - Wing Skins
Ability to lay up curves of Airfoils
Cheapest that met criteria of foams
Aramid Core
- Spar, Aft Spar, Rib
Light Weight
Cheapest per Pound

34. Adhesive Options
DP 420
3M, Two Part Epoxy
From 3M Epoxy Comparison

35. Adhesive Options (Cont.)
PTM & W:
ES6292 Lightweight Tough Epoxy Adhesive
Two Part Epoxy
Designed for use in the structural assemblies involving composites
Already used by Cirrus Design Center

36. Adhesive Testing Objectives: Test Max Adhesive Loads
Need to make sure adhesives aren’t effected by surfaces
Test surface preparation techniques

37. Adhesive Testing (Cont.)
Materials Tested:
Adhesives:
PTM & W ES6292
3M DP 420
Composites:
Aramid Core with Fiberglass Skin
HT Diab Foam Core with Tencate Fiberglass

38. Adhesive Testing (Cont.)
Tensile Test:
Load Bonds in Tension
Measure Load at Fracture
Calculate Lbs/In. Bond Strength
Test Equipment:
Constant Strain Load Cell
Measures Load
and displacement

39. Adhesive Testing (Cont.)

40. Adhesive Testing (Cont.)
Tensile Load Justification:
Jaws:
2° freedom on both directions
Top & Bottom
All samples were applied within 1 degree of perpendicular
Therefore:
Tension loads were perpendicular to bond

41. Adhesive Testing (Cont.)
Surface Preparation:
All surfaces were lightly sanded to rough up surface
All surfaces were cleaned with to remove

42. Adhesive Testing (Cont.)
Results:
Bond Strength per Inch of Bond (Lbs/In)
PTM & W ES6292= 81.7 ± 4.1 Lbs/In
3M DP 420=87.1 ± 4.4 Lbs/In
Uncertainty Estimated at 5%

43. Adhesive Testing (Cont.)
Conclusions:
Adhesives were comparable in
Strength per Inch
Both Adhesives meet strength requirements for wing
PTM & W ES6292 Adhesive is better because of lower cost

44. Adhesive Testing (Cont.)
Errors:
Improper preparation:
Issue: Samples broke at surface
Resolution: Better Surface Preparation
Sanding (possibly Sand Blasting)
Better Removal of oils from surface
Effect:
Bonds Broke Prematurely
With Better Preparation Bonds could hold more Weight

45. Adhesive Testing (Cont.)
Test Equipment:
Issue: Jaws Slipping
Resolution: Better Transition from Material to Jaw
Adhere Aluminum Tab into Composite
External Clamp System with Aluminum Tab for Jaw
Allow Material to be secured by clamp and Jaw to attach to Aluminum Tab
Effect:
Load might be underestimated.
Result: Bond Strength could be higher than reported

46. Adhesive Testing (Cont.)
Further Testing:
Shear Test Side View:

47. Adhesive Testing (Cont.)
Shear Test Top View:
(Load Pulling out from picture)

48. Adhesive Testing (Cont.)
Shear Test:

49. Structures Tyler Hawkins
Cirrus Wing
Structures
Tyler Hawkins

50. Structure Goals Light Weight < 170 lbs. in total
Handle All Loads with Extra Safety Factor
Maintain Aerodynamic Shape
Attach to Fuselage Structure

51. Component Break Down
Wing Skin
Main Spar
Aft Spar
Ribs
Leading Edge Braces

52. Wing Skin NEEDS Light Weight Easily formed into complex surfaces
Durable
Puncture and Tear Resistant

53. Solutions Use 2-Core-2 construction for the wing Fiberglass 45o angles
.25 inch
Density = lb/in3

54. Wing Skin Lay Up

55. Reasoning Process is known and used at Cirrus
Creates a Very puncture resistant material
Fiberglass performs well in multiple directions
±45 degree orientation
Light Weight material
Possible Improvements
Cut away sections of Foam where not needed
Use Honeycomb Aramid Core to cut weight

56. Main Spar NEEDS Light Weight Handle Compression, Tension, and Shear
Provide Bond Surface for Ribs and Skin
Serve as Attachment to Fuselage

57. Spar Designs Considered
C-Channel
Provides Good Bonding Surface
Would be made Entirely of Carbon
Similar to Existing Cirrus Designs
Why Not
Looking for Two Piece Main Spar Assembly
Incorporating Aramid Core Can Lighten Structure

58. Rectangle Spars 4 – Core – 4 Why not? Simple Design 1 Piece Core
One Width Carbon Cap
Why not?
Too thick adds core weight
Too thin makes carbon lay up with many thin strips

59. Examples of Rectangle Spars

60. I-Beam Spar
Provides Similar Shear, Tension, Compression coverage to Rectangle
Thinner Shear Web
Very Light Weight
Provides Large Bonding Surface to Wing Skin
Potential Drawbacks
Upfront Tooling
Layup Complexity

61. Caps Carbon Laid Up as T-shape Carbon Strips
Tensile Strength: 2.62*105 Psi
Compressive Strength: 1.42*105 Psi
Absorbs Forces on Top and Bottom of Spar at Low Weight Cost

62. Spar Web Core .3 inch Aramid Core
Very Light Weight
Bonds Well To Cirrus’s Fiberglass
4 ply fiberglass quilt on both Sides of Core
Provides the Shear support
Alternate Ply orientations (±45 degrees)
Performs very well in Shear (23800 Psi Shear strength)
Low Cost and Ease of Use

63. General Lay Up Scheme

64. Spar Dimensions Root Tip Total Height 7.3 5.2 Web Width 0.38 Cap Width1
tupper cap
0.25
0.06
tlower cap
0.12
talpha
0.1
*All units in Inches

65. Specific Modifications
Taper Layers Until 4 Layers Left
Run 4 Layers to End Plus Alpha Section
Allows for Wide Bond Area
Need to only cut two strip Widths (α and cap)
Taper These Quickly at the end of the Spar to Avoid Large Stress Concentration

66. Connection To Fuselage
Fuselage Width: 48 in.
Extend Both Spars Through Fuselage
Attachments
2 Hard Points for Bolts Between Spars
Bracket for Spars to Transfer Load to Fuselage
1 Hard Point each Rear Spar 6 Inches into Fuselage

67. Attachment Point

68. Hard Points Options Chose Aluminum Plug Laid Into Spar
Fiberglass Laid In Through Entire Spar
Aluminum Plug Laid Into Spar
Aluminum Plug Glued Into Spar
Chose Aluminum Plug Laid Into Spar
6061-T6
Light Weight
High Bearing Strength

69. Hard Point Dimensions Use .75 inch bolt/plug to attach structure
0.3 inches thick
3.75 inches in diameter
Spacing of 46 inches on center, 23 on either side of WS0.

70. Aft Spar Simple Design 2-Core-2 Aramid Core
2 layers of Glass on Each Side
No Caps-Only Shear Felt Here

71. Ribs and Leading Edge Supports
2-Core-2 Construction
Aramid Core
Can Make Sheets of This and Water Jet Cut Specific Panels
Also Aft Spar
Provide Bond Length to Hold Skin and Structure Together

72. Rib Spacing
Airplane Design by Jan Roskam suggest 36” spacing for Light aircraft.

73. Length of top of Rib (In.) Weight held before bond fracture (Lbs)
Rib to Skin Bonding
Rib (Root to Tip)
Length of top of Rib (In.)
Weight held before bond fracture (Lbs) 1
25.08
2,127 2
23.37
1,982 3
21.31
1,807 4
19.61
1,663 5
16.88
1,432
Spar
180
15,266
Wing Loading
24,277
Total Weight Held
4320 lbs
5.62
Safety Factor

74. 3-D view of Interior Structure

75. Structure with Skin Attached

76. Weight Estimate Component Weight (lbs) Wing Skin 52.20
Main Spar (w/ H.P.’s)
14.35
Aft Spar (w/H.P.)
2.06
Ribs
1.879
L.E. Braces
0.872
Glue (over estimate)
3.500
Total
74.86

77. Cirrus Wing
Build/Test
Nick Brown

78. Manufacturing and Assembly Bryce Holmgren
Cirrus Wing
Manufacturing and Assembly
Bryce Holmgren

79. Manufacturing Part Fabrication
Spars made using semi-automated system

80. Manufacturing Part Fabrication
Ribs and shear web water jet cut from single sheet of Nomex/glass composite
Ventilation required when machining produces dust, mist or vapor
Light Hand Cotton gloves for General Protection

81. Manufacturing Part Fabrication
Wing skins assembled in custom tooled forms

82. Manufacturing Final Wing Assembly

83. Manufacturing Final Assembly

84. Manufacturing Epoxy Health Concerns
Effects of Overexposure:
Eyes: Causes severe conjunctive irritation, Corneal injury and Iritis
Skin: May cause irritation, burns, ulceration, or skin sensitization
Inhalation: Vapors are irritating and cause tears, burning of nose and throat, coughing, wheezing nausea and vomiting
Ingestion: Moderately toxic, may cause mouth and throat burns, abdominal pain, weakness, thirst and coma.
Chronic: Amine vapors may cause liver and kidney injury. Eye, skin or lung may develop or be irritated by Amine vapors.
[From MSDS of ES6292B with Beads]

85. Manufacturing Safety Precautions
Respiratory: Not required unless process is creating dust, mist or vapor.
Ventilation: Breathing of vapor must be avoided.
Hand Protection: Impervious gloves, neoprene or rubber, must be worn
Eye Protection: Splash proof Goggles or safety glasses
Other: Clean body covering clothing and shoes
[From MSDS of ES6292B with Beads]

86. Business Case
David Gustafson

87. Project Goals Design a Composite Wing Meet Design Criteria:
Comoposite Panels
Edge Bonding Technique
Meet Design Criteria:
170 Lbs or less
No Spin Criteria in Airfoil

88. Financial Summary Upfront Costs: Wing Lay up Structure Final Assembley
Safety Equipment
Gloves
Goggles
Respirators
Water Jet Cutting Equipment
Alternate Option:
Contract for pieces to be Water Jet Cut

89. Financial Summary Material Cost of Wing: Total: ~$1700 Carbon: $123
Aramid Core: ~$840
Foam: ~$300
Fiberglass: ~$400
Adhesive: ~$100
Total: ~$1700

90. Justification Structure Meets Design Loads Manufacturing Process
Bonds Safety Factor >5
Manufacturing Process
Streamlined
Cost Effective
No Spin
Drooped Leading edge in Airfoil

91. Justification Edge Bonding Allowed for a low weight design
Less Complex Manufacturing System
Meets strength Criteria

92. Thank You For Your Time and Consideration